This invention relates to vacuum pumps and is particularly concerned with reducing exhaust noise thereof.
Vacuum pumps, particularly small high speed vacuum pumps, can be very noisy in operation. Most noise emanates from the exhaust area and is a result of air being pumped out in a series of rapid undamped blasts. It is possible to fit a silencer to the exhaust port, but such silencers increase the pump cost and may add to the overall pump size at a time when manufacturers are seeking to minimize size cost and material content as much as possible.
High speed electrically driven vacuum pumps for vehicles pose particular problems since it is essential that such pumps are very quiet in operation yet take up the minimum space possible. Such pumps should be adaptable to many different installation sites yet be of a common reliable and economical design. Above all such pumps must not be unduly expensive.